This invention relates to electromagnetic interference (EMI) shields.
Modern computer equipment is required to provide EMI shielding for openings in the equipment housing in order to meet EMI emissions standards. However, the shielding of such apertures can conflict with the need to provide adequate ventilation for the equipment.
Where the EMI shielding is used to fill an opening for the insertion of a removable component, for example a removable media drive, there is a need to make the EMI shielding readily removable, preferably without the need for tools.
The present invention seeks to provide electromagnetic shielding that addresses these conflicting requirements.
A first aspect of the invention provides an electromagnetic interference (EMI) shield for location in an aperture in a wall of a system unit housing. The electromagnetic interference shield is integrally formed from sheet metal. It comprises a perforated substantially planar portion (or plate) with fingers defined around the periphery thereof. A plurality of first fingers are preformed to define abutments to abut against an outer surface of the wall and a plurality of second fingers are preformed to sprung latches for latching within the aperture.
The combination of first and second fingers means that the EMI shield can be located in the aperture in a removable manner without the use of tools. The perforations in the planar portion are configured to permit ventilation of the interior system housing while preventing EMI interference radiating from the system housing. The substantially planar portion has approximately the same shape as the aperture to be filled and is slightly smaller than the aperture, a gap around the planar portion being occupied by the fingers.
In an embodiment of the invention, the first fingers alternate with the second fingers along at least one edge of the substantially planar portion. This provides for reliable location of the EMI shield in the aperture.
In one example, the first fingers comprise a first portion that extends substantially perpendicular to the substantially planar portion, a second portion that is folded back on the first portion and a third portion that extends away from and substantially parallel to the plane of the substantially planar portion. The second fingers comprise a springy portion that extends generally perpendicular but slightly outwardly with respect to the substantially planar portion and an angular latching portion at the end of the springy portion.
In an example of the invention the second fingers extend to the rear of the substantially planar portion, the electromagnetic interference shield further comprising a handle portion at the periphery of the substantially planar portion, the handle portion extending to the front of the substantially planar portion. This facilitates the insertion and removal of the shield. The EMI shield can be used for covering an aperture of a media drive bay.
The preferred embodiment of the EMI shield is stamped and folded from stainless steel.
Another aspect of the invention provides a system unit comprising a housing, an aperture in a wall of the housing providing access to a drive bay and an electromagnetic interference shield as set out above and located in the aperture.
A further aspect of the invention is a method of providing electromagnetic interference shielding for an aperture in a wall of a system unit housing, the method comprising removably locating in the aperture an electromagnetic interference shield that is integrally formed from sheet metal, the electromagnetic interference shield comprising a perforated substantially planar portion with fingers defined around the periphery thereof, a plurality of first fingers being preformed to define abutments to abut against an outer surface of the wall and a plurality of second fingers being preformed to define sprung latches for latching within the aperture.
Further aspects and advantages of the invention will become apparent from the following description of a particular embodiment.